Process for curing polymerizable esters in presence of organic hydroperoxide and metallic driers



PROCESS FOR CURING POLYMERIZABLE ESTERS IN PRESENCE OF- ORGANIC HYDROPEROXIDE 5 metha'crylate and allyloxymethyl methacrylate. Of these AND METALLE DRIERS we find the polyesters of the succinic acid ester of the G y Lambsill s Maienhead, and Pete! Frannt-allyl ether of glycerol and the phthalic acid ester of cis Ni k Hol ort, England, assignors to Imperi the ct-allyl ether of glycerol to be the most suitable since Chemical Industries i England a they are non volatile at normal temperatures and do not Pm'amm 0f Great Bmam decrease the viscosity of the laminating resin. A further No Drawing. Application September 19, 1955 important practical advantage is that they are relatively Serial No. 535,266 odourless whereas some of the monomeric compounlcils ossess pungent lachrymatory' odours which can ma e Clams g a i gz Bmam I i heir usage unpleasant. The proportion of'additive used eptem er with the polymerisable methacrylate and acrylate esters 3 Claims. (Cl. 260-4531) can be varied between fairly wide limits butwe find additions which give surface coatings of the order of 4-16 This n nti r l to the curing of polymerisable mgms. additive per square inch of surface in contact with esters Whose polymerisation is inhibited y the Presence air to be most useful. This is equivalent to an addition of oxygen. of 520% by weight of additive based on weight of poly- The polymerisable esters it which we a concerned merisable ester in the surface film. The viscosity of the in this invention include monomeric esters of methacrylic preferred polyester additives i hi h and the molecular and acrylic acid and polyesters derived from a polyhydric weight of these additives is preferably between 7000 and alcohol, a dicarboxylic acid and methacrylic or acrylic 10,000. acid, p resins described in British Patent A possible explanation of our invention is that the- 607,8 88, having the general formula: allylic compound absorbs atmospheric oxygen at a rate CHi=CCO O-CHT CHQ -OC /C0--CHiCHi0c0c=c OH: I- I J CH:

O where n is 0 or a small positive integer, i.e. between 0 greater than the rate at which oxygen diifuses, by soluand 5. tion, into the system hence the actual curing reaction It is known that polymerisable polyesters, having distakes place under substantially anaerobic conditions. solved in them polymerisable substances such as styrene Some support for this theory is to be found in the or a diallyl ester or certain methacr-ylates, can be gelled fact that it is known that the formation of hydroperin the presence of organic peroxides, and for example, oxides by addition of oxygen to allylic compounds is a cobalt naphthenate. Naphthenates and similar salts of facile reaction. More particularly, compounds containmetals other than cobalt have also been used, including 40 ing the allyloxymethyl group in which the methylene lead, iron, copper and manganese. All of these salts are groups adjacent to the ether oxygen are very prone to known as driers. It is also known to use a hydroattack by oxygen with the resultant formation of hydroperoxide and a drier to cure certain mixtures comprisperoxides. ing a copolymerisable mixture of one or more alkyd It is possible that the driers assist our additives in resins comprising an a,fl-unsaturated acid and one or 4.5 overcoming air inhibition but they are not effective themmore -substances comprising the CH -C group. This selves in the absence of our additive; latter process is stated to eifect curing at room or higher For the preparation of laminated materials the additemperatures. 7 tive can be mixed with the bulk of the laminating resin "The present invention concerns a method of overcomor a solution in, for example, glycol dimethacrylate may ing the characteristic air inhibition of polymerisable meth be sprayed or brushed onto the outer layer of the lamiacrylate and acrylate esters. For example, it is known nated body. A third procedure involves the mixing of that with. certain resins used in laminated productions the additive with the laminating resin used to impregnate the curing process in the exposed layers is inhibited by the outer layers of the laminate. the presence of atmospheric oxygen. Similar difliculties The catalyst and drier may be added to the metharise when coatings are formed comprising polymerisable acrylate polyester resin before the allyloxymethyl group methacrylate and acrylate esters. containingcompoun-d or the three compounds may be We have now found that the air inhibition associated added individually or all together as a mixture. The with polymerisable methacrylate and acrylate esters can glycol dimethacrylate can be used if necessary and is a be overcome by effecting the curing of the esters in the polymerisable solvent. presence of a hydroperoxide curing catalyst, a drier Our invention is illustrated bythe following examples and in addition a compound containing the allyloxyin which parts are expressed by weight. methyl group CH CH.CH -O- CH Catalysts ink [e I elude aliphatic, aromatic and cycloaliphatic hydroperp 1 t oxides and examples of such catalysts for use with the 4A nineteen layer 1511minate p p 011 a Solid additive include cyclohexyl hydroperoxide, methyl ethyl using 100111 State 81855 610th and impregnating ketone hydroperoxide, 'di-isopropyl benzene, hydrop'er- I throughout With resin oxide, paramenthane hydroperoxide, tertiary butylhydro- Resin A: a peroxide and cumene hydroperoxide. The most satis- Ethylene glycol methacrylate/phthalate resin factory catalysts from, the view point of eificiency are prepared as described in Example 7 of British cycloh'exylhydrop'eroxide and methyl ethyl ketone hydro Patent 607,888

peroxide. Satisfactory driers for use in the invention atent include cobalt or lead naphthenates. Examples of the r 2,928,804 Patented Mar. 15, 1960 ice glycerol a 10 2,9as,so4.

Example 7 of British Patent 607,888 reads as followsz 2.5 parts'concentrated sulphuric acid, 124 parts ethyl ene glycol (2 mols.), 148 parts phthalic anhydride (1 mol.), 300 parts trichloroethylene were charged into a well-stirred glass vessel from which water could be removed by azeotropic distillation, the trichloroethylene being returned to the vessel after condensation. When 18 parts of water had been removed the reaction mixture was cooled to room temperature and 172 parts methacrylic acid and 8 parts hydroquinone disulfonic acid added. The azeotropic distillation was then continued accompanied by the bubbling of a stream of air through the mixture until all the water (36 parts) had been removed.

20 parts of anhydrous sodium carbonate were added and the mixture obtained stirred for half an hour. The mixture was filtered through a small pressure filter and the filtrate transferred to an enameled vessel from which the trichloroethylene was removed by distillation under reduced pressure so that the temperature of the solution did not rise above 50" C. A pale yellow viscous liquid consisting essentially of dimethacrylic esters of low molecular weight dihydroxy glycol phthalate was obtained. The laminate was exposed to the air and the surface was tack free in six hours.

Example 11 A nineteen layer laminate was prepared as follows. Fifteen layers of glass cloth were impregnated with resin B and each laid on the solid former. The top four layers of glass cloth were then each impregnated with resin A and added to the original fifteen layers.

100 parts by wt. resin B: Ethylene glycol methacrylate/phthalate resin as used in Example I. Drier" and catalysts as in Example I.

The laminate cured satisfactorily and the surface was found to be tack free in six hours.

Example Ill Example I was repeated using in place of the phthalic acid ester of the u-allyl ether of glycerol, the succinic acid ester of the m-allyl ether of glycerol, and similar results were obtained.

Example IV A similar ten layer laminate was prepared using resin CHFC-C -0 of the a-allyl ether of glycerol in place of the phthalic acid ester of the a-allyl ether of glycerol and similar results were obtained.

Example VI A ten layer laminate was prepared as in Example IV. The surface was brushed with solution C. Results were again satisfactory, the applied film being 10 thou. inch thick.

Example VII A ten layer laminate was prepared as described in Example IV. The surface of the laminate was brushed with resin A. Results were again satisfactory and the film comparable with that obtained in Example VI.

It is essential, when employing the coating techniques, that the exposed surface of the methacrylate polyester resin containing mass be completely covered with the solution containing the additive if the air inhibition characteristics of the methacrylate polyester resins are to be overcome. The process as used in Examples IV, VI and VII has the advantage that the amount of additive required to overcome the air'inhibition is very small and has been shown to be of the order of 9 mgrn. of additive per square inch of laminate.

Our invention is also applicable to coating and impregnating compositions where air inhibition is in some a problem.

Example VIII A sample of resin A was poured onto tinplate to form a thin film. This film cured satisfactorily in six hours.

Example IX A further sample of resin A was stored in a 3" x 1" tube open at one end and this cured to a hard, tack-free, state in live hours.

Example X A solution of 50 parts of the phthalic acid ester of the. aallyl ether of glycerol and 50 parts of methyl meth-- acrylate was treated with catalyst and drier as in the above examples. A sample was brushed onto tinplate and the film cured in air in three and a half hours to give a good, hard, tough, film.

Example XI B throughout- Whefl P p the exposed surfaces of wherein n is a positive integer between 0 and 5, in the the laminate were sprayed with a solution containing: Solution C:

Glycol dimethacrylate 90 The phthalic acidester of the u-allyl ether of glycerol 10 The solution formed a film about 5 thou. inch thick and the laminate appeared to be cured satisfactorily and the surface wa again tack freeinsix hours.

Example V Example IV was repeated using the succinic acid ester GHFO-C O of the order of I' n CHFC-C O CHa-CHr-O-G 6 wherein n is a positive integer between 0 and 5, in the presence of a catalyst selected from the group consisting of aliphatic, aromatic, and cycloaliphatic hydroperoxide curing catalysts, and a metallic salt drier, the improvement which comprises incorporating therewith an amountof from 5 to 20%, by weight of said polymerizable ester, of the phthalic acid ester of the q-allyl ether of glycerol.

References Cited in the file of this patent UNITED STATES PATENTS 2,399,214 Evans 2,437,508 DAlelio 2,594,825 Tawney 2,642,410 Hoppens 2.852.487

Maker Apr. 30, 1946 Mar. 9, 1948 Apr. 29, 1952 June 16, 1953 Sept. 16, 1958 

2. IN A PROCESS FOR CURING A POLYMERIZABLE ESTER HAVING THE GENERAL FORMULA 